Background: Atopic dermatitis (AD) is a chronic inflammatory disease associated with pruritus and sleep loss. Pine-tar has long been used for various chronic skin conditions in which its polycyclic aromatic hydrocarbon (PAH) component is anti-inflammatory and its resin acids antiseptic. The null hypothesis of this trial is that there is no difference in clinical efficacy between a pine-tar product and its vehicle for AD.
Methods: A 3-month, investigator-blinded, crossover, randomized control trial (RCT) was conducted in which each patient was assigned to bathing with pine-tar bath oil for one month and vehicle bath oil for another, with a washout period of 1-month in-between. Acceptability and efficacy of the bath products were measured. Disease severity scores (scoring atopic dermatitis (SCORAD) and patient-oriented eczema measure (POEM), quality of life questionnaires, noninvasive skin biophysiological measurements, blood IgE levels, and Staphylococcus aureus (SA) colonization status were assessed before and following bathing.
Results: Significant improvements were found in total SCORAD (p = .030), POEM (p = .004), SA colonization status (p = .002), and log-transformed IgE level (p = .009) among patients who bathed with pine-tar in the overall RCT study using intention-to-treat analysis. For per protocol analysis, significant improvements were found in total SCORAD (p = .024), objective SCORAD (p = .011), extent (p = .014), intensity (p = .032), pruritus (p = .047), POEM (p = .044), SA colonization status (p = .035), and log-transformed IgE level (p = .028). Acceptability to both bath-oils was good, and no product-related serious adverse events were recorded.
Conclusions: Bathing with pine-tar is an efficacious and recommendable adjuvant practice for AD patients. Disease improvement is associated with reduction of SA and IgE.
Keywords: Pine-tar; atopic dermatitis; bathing; crossover; randomized clinical trial.